how do you react with unethical behaviour occur in business today?

I think you are confusing two separate but possibly related issues here. Ethical business and fraud. It is not true that all non-ethical business is fraud and it is also not true that all ethical business is not fraud. People are in business for varuious reasons, mainly but not exclusively to make money. If there are ways of making more profit and hence employing more people is that less ethical than deciding not to expand? I think it depends on your definition of 'ethical'. In UK we have minimum wage levels and significant levels of employee protection laws so it is rare for employees to be exploited. It is difficult to find ways to be fraudulent. Of course a small number of people try to find ways of making money illegally. However there are many things that might be unethical it depends what you mena by this vague and media inspired phrase.